A wide band is a LINEAR 02 reading and display of (hopefully:icon_bigg )corresponding a/f ratio(~9.0-18.0, and all points in between), so you find out exactly what is going on. Think of the stock 02 like a computer , which only knows 0 and 1. Thats what it does, if it senses a lot of 02 it sends a 1, if it doens't sense much it sends a 0 (not really, it sends different voltages, but the analogy applies). But becuase you don't know HOW rich or lean, it doens't help you with tuning. It will say "lean" if somewhat above stoich or if you at 22.0 and melting your engine, you don't know.
If you mess with your air and fuel with mods, then you will likely want to know what is going on unless someone who knows exactly what they are doing has tuned your car for you and you don't mess with it. But then again its always good to know when circumstances change. again, the stock 02 is useless for this, its not there to be a tuning tool.... just for emissions
I think its unfortunate that the stock is referred to as a "narrow band" and the WB as a "wideband," when in fact they are two totally different animals, and are not interchangable nor comparable, so the similiar names are misleading....